Thyroid cancer: is the incidence rise abating?
OBJECTIVE
The aim of the present study was to determine recent trends in thyroid cancer incidence rates and to analyze histopathological characteristics and geographical distribution.


METHODS
Histologically proven 5367 cases were collected over the period 1998-2006 in France from the Rhône-Alpes thyroid cancer registry. Geographical variations of incidence were analyzed using a mixed Poisson model.


RESULTS
The average incidence rates, age standardized to the world population, were 3.9/100,000 in men and 12.3/100,000 in women, higher than those previously reported in France. After an initial increase during the first 3 years, a steady level of incidence was observed for the period 2001-2006. The annual incidence rate of microcarcinomas was correlated with that of all cancers in men and women (r=0.78 and 0.89; P<0.01) respectively. Papillary microcarcinomas represented 38% of tumors and two-thirds of them measured less than 5 mm in diameter. They were fortuitously discovered after thyroidectomy for benign diseases in 64% of cases. Histological marks of aggressiveness differed according to the size of the tumor. Despite recent advances in diagnosis, 13% of tumors were diagnosed at advanced stage especially in men. Geographical distribution of incidence based on subregional administrative entities showed lower incidence rates in rural than in urban zones in men (relative rate: 0.72; 95% CI: 0.62-0.84) and women (relative rate: 0.85; 95% CI: 0.73-0.93).


CONCLUSIONS
The present study suggests that the rise in thyroid cancer incidence is now abating. It could reflect standardization in diagnostic procedures. Further studies, performed on a more prolonged period, are necessary to confirm these data.
Sassolas
Geneviève
G
Hospices Civils de Lyon, Registre Rhône Alpin des Cancers Thyroïdiens, Fédération d'Endocrinologie et Centre de Médecine Nucléaire Groupement Hospitalier Est, Bron, France.
Hafdi-Nejjari
Zakia
Z
Remontet
Laurent
L
Bossard
Nadine
N
Belot
Aurélien
A
Berger-Dutrieux
Nicole
N
Decaussin-Petrucci
Myriam
M
Bournaud
Claire
C
Peix
Jean Louis
JL
Orgiazzi
Jacques
J
Borson-Chazot
Françoise
F
D002291:Carcinoma, Papillary / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012424:Rural Population; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology; D014505:Urban Population